Colored liquid composition for editing pen

ABSTRACT

The colored liquid composition of the invention for a highlighter comprises a coloring element and water, the water content by weight lies in the range 10% to 30%. In addition, it comprises at least 40% of a liquid component having surface tension greater than 40 mN/m. In a variant, the coloring element is a tracer solvent having a fluorescent appearance under basic pH, in particular hydroxypyrenetrisulfonic acid, the pH of the composition lying in the range 8 to 9, and the component having surface tension greater than 40 mN/m is triethanolamine. Under such circumstances, the composition contains an acid to neutralize the triethanolamine in part in order to obtain the basic pH, for example hydrochloric acid.

This application is a national stage filing of International ApplicationNo. PCT/FR01/04131, filed Dec. 20, 2001, which claims priority to FrenchPatent Application No. 00/16946 filed Dec. 22, 2000, the entire contentsof which applications are incorporated in their entirety herein byreference.

The present invention relates to a colored liquid composition for awriting instrument for highlighting or marking the colored liquidcomposition is suitable for use in a text that has already been writtento draw attention optically to the passage of said text that has beenhighlighted.

BACKGROUND OF THE INVENTION

Three types of colored liquid compostions or inks are already known forhighlighting pens that serve to highlight text or make it stand outoptically.

In the first type, the ink is a traditional colored ink in which thedye(s) is/are at low concentration so as to avoid masking the text whichis to be highlighted. Generally such an ink is based on a solventcontaining about 70% water and 30% diethylene glycol.

In the second type, concentrated ink is used containing 50% water and50% fluorescent dye coated in resins that are put into emulsion inwater. The concentrated ink is used for making the colored liquidcomposition for use in the highlighter at a concentration of 20% to 30%by weight, with the reminder of the composition being constituted by awater-retaining agent such as glycerin, sorbitol, diethylene glycol, ortriethylene glycol which avoids the tip of the writing instrument dryingout too quickly.

In the third type, the colored liquid composition makes use ofwater-soluble fluorescent dyes and requires the physico-chemicalcharacteristics of the composition to be adapted to obtain a compromisebetween the fluorescent effect and the properties of the writinginstrument in use. By way of example, a colored liquid composition ofthis type is disclosed in document EP 0 464 304, which composition isbased on an aqueous solution of hydroxy-pyrenetrisulfonic acid withbasic pH. Such a composition contains 5% to 20% by weight compared withthe total weight of liquid of mono-, di-, or trisaccharides obtained byreducing the polyols from which they are derived or by mixing saidsubstances.

Colored liquid compositions for highlighters, in all three of theabove-specified types, present the same defect when highlighting textthat was previously written using a fountain pen or a roller (ball felttip) having an ink formulation based on water-soluble dyes. Under suchcircumstances, it is found that the colored liquid composition of thehighlighter moistens the ink of the text and partially dissolves thedyes contained in said ink. As a result the dyes constituting thewritten text become smeared in the highlighted passages, giving aparticularly unpleasing appearance. Furthermore, the tip of thehighlighter is also polluted to some extent by the dyes that it haspartially dissolved from the ink of the written text.

OBJECT AND SUMMARY OF THE INVENTION

The object of the invention is to mitigate the above-mentioneddrawbacks.

This object is well achieved by the colored liquid composition for ahighlighting pen which, in known manner, comprises water and a coloringelement. In characteristic manner, the colored liquid compositioncontains a water content by weight of 10% to 30% and a content by weightof at least 40% of a liquid component having surface tension greaterthan 40 millinewtons per meter (mN/m).

The presence of a small amount of water makes it possible to usecoloring elements that are water-soluble while nevertheless not enablingthe dyes contained in the writing ink for highlighting to be dissolved.The content of the liquid component having a surface tension in excessof 40 mM/m prevents the colored liquid composition from penetrating intothe writing medium, when the medium is paper.

In a preferred embodiment, the coloring element is a tracer solventwhose fluorescent appearance is revealed at basic pH, such ashydroxypyrenetrisulfonic acid (pyranine, color index solvent green 7 No.59040) with pH lying in the range 8 to 9. Under such circumstances, thecomponent having surface tension greater than 40 mN/m istriethanolamine, which has been partially neutralized by an acid, inparticular hydrochloric acid so as to obtain the basic pH lying in therange 8 to 9. This neutralization makes it possible to enrich the colorliquid composition with a quaternary ammonium salt which limitspenetration of the composition into the writing medium when the mediumis paper. In addition, it has been found that if this hydrochloric acidneutralization is not performed, then the colored liquid compositionpresents viscosity that is too high to allow the ink to diffuse normallyin the capillary lattice of the writing instrument, because of the largecontent of triethanol-amine. This neutralization serves to lowerviscosity under conditions that enable the instrument to operatenormally.

The viscosity adjustment required for normal operation of the instrumentcan also be achieved by a certain amount of primary alcohol, lying inthe range 1% to 20% by weight. The alcohol may be ethyl, propyl, orbutyl, for example.

In addition, limiting the penetration of the colored liquid compositioninto the paper medium can be further adjusted by using an acrylic resinin emulsion in the composition, at a concentration of about 2% to 15% byweight.

Naturally, it is possible to use other types of coloring element, inparticular a water-soluble fluorescent dye such as acid blue No. 9, forexample.

Furthermore, it is appropriate on a case-by-case basis to select theliquid component whose surface tension is greater than 40 mN/in, e.g.from the group consisting of ethanolamine, triethanolamine, glycerin (orglycerol), sorbitol, and glycols.

The preferred liquid component is the reaction product of glycerin (orglycerol) and urea, giving the following developed formula:

Its surface tension is about 64.5 mN/in and its viscosity is about 150centipoises (cPo). A larger quantity, therefore, can be incorporated,about 80%, with a corresponding reduction in the quantity of water,about 10% in the colored liquid composition for highlighting, comparedwith other components that are more viscous, such as glycerin.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be better understood on reading the followingdescription of embodiments of a colored liquid composition forhighlighting based on hydroxypyrenetrisulfonic acid in an alkalinesolution.

Document EP 0 464 304 discloses a colored liquid composition suitablefor use in writing instruments of the highlighter or marker type, whichis based on an aqueous solution presenting a pH situated in the alkalinerange, hydroxypyrenetrisulfonic acid known under the name pyranine,referenced color index solvent green 7 No. 59040. In that document, thecolored liquid composition contains 5% to 20% by weight relative to thetotal weight of liquid of mono-, di-, or trisaccharides coming from thereduction of the polyols from which they derive, or of a mixture of saidsubstances. According to that document, such addition of mono-, di-, ortrisaccharides makes it possible to obtain overlining of exceptionalquality on the widest variety of types of paper with very greatimprovement in the fastness of the marking in relation to light.

However, according to the Applicant, when the highlighting is performedon text written with a fountain pen or with a roller, using inkformulated on the basis of water-soluble dyes, the dyes in the passagebeing highlighted are smeared, and the tip of the highlighter is alsopolluted to some extent with said dyes.

The colored liquid composition whose formula by weight is given belowserves to avoid those drawbacks. This composition is likewise based onpyranine in an alkaline solution.

-   -   Pyranine (color index solvent green 7 No. 59040): 1% to 3%    -   Triethanolamine 85% (neutralized with 22 moles concentrated        hydrochloric acid): 42.5% to 70%    -   Water: 10% to 30%    -   Acrylic styrene resin emulsion with 50% water: 2% to 15%    -   Primary alcohol: 1% to 20%        Triethanolamine has surface tension of 47.5 mN/m. Adding        concentrated hydrochloric acid serves to neutralize the        triethanolamine in part so as to reach a pH in the range 8 to 9,        which is necessary for revealing the intense fluorescent yellow        effect of pyranine. The acrylic styrene resin in emulsion may be        constituted, for example, by the product sold under the        reference Joncryl J90 by the firm Goodrich.

The primary alcohol is preferably ethyl alcohol, propyl alcohol, orindeed butyl alcohol.

The purpose of adding the primary alcohol is to reduce the viscosity ofthe colored liquid composition without significantly reducing itssurface tension which needs to be maintained high enough to prevent thecomposition from passing through the paper medium, which would have theeffect of spoiling the reverse side of the sheet on which thehighlighter is used.

The particular feature of the colored liquid composition of theinvention is that it satisfies all of the following requirements:

-   -   it reveals the fluorescent character of pyranine by the alkaline        pH of the composition;    -   it enables the pyranine to be dissolved because of the presence        of water;    -   its viscosity is low enough to enable the composition to diffuse        in normal manner in writing instrument, by capillarity;    -   its surface tension is high enough to limit penetration of the        composition into a paper medium; and    -   it has a quantity of water that is small so as to avoid        entraining water-soluble dyes from the ink in the passage being        highlighted.

All of those requirements are satisfied by the colored liquidcomposition whose formulation by weight is given above. Nevertheless,the present invention is not limited to that particular implementationwhich uses pyranine as the coloring element and triethanolamine as thecomponent having surface tension greater than 40 mN/m. Other types ofcoloring element can be used, in particular water-soluble fluorescentdyes which do not need to have a basic pH.

Whatever the coloring element used, it is possible to use other liquidcomponents having surface tension greater than 40 mN/n, e.g. glycerin(or glycerol), sorbitol, or glycols.

The surface tension of glycerin is about 72 mN/m, but its viscosity isvery high, being about 1200 cPo. It is suitable, but it requires a watercontent that is rather high, about 25%.

A preferred component is C₄H₆O₄ which is the result of reacting glycerinwith urea and which has the following developed formula:

This has a surface tension of about 64.5 mN/m, but its viscosity isabout 150 cPo. This makes it possible to use a minimum water content of10%.

In the two examples below, A and B are liquid compositions havingsimilar formulations, using glycerin (A) or the component C₄H₆O₄ (B).

(A) (B) pyramine    3%   3% glycerin 64.75%   0    C₄H₆O₄ component   0    80.5% water    25%   10% neutralized triethanolamine  0.55% 2.5% n. propanol    4%   4%

It should be observed that the viscosity value needed for normaloperation of the instrument is a function of the elements constitutingthe instrument, such as its writing head, its capillary connector, thefibers and the bonding agents making up the fiber reservoir. It is thuspossible to select said elements to take account of the viscosity of thecolored liquid composition, or conversely to select said composition asa function of the instrument. By way of non-inclusive indication, theviscosity of the colored liquid composition for normal operation of ahighlighting instrument may lie in the range 10 cPo to 30 cPo.

1. A colored liquid composition for highlighting, the compositioncomprising water and a coloring element, wherein the water content byweight lies in the range 10% to 30% and wherein the compositioncomprises at least 40% of a liquid component having surface tensiongreater than 40 mN/m, wherein the liquid component having surfacetension greater than 40 mN/m is a C₄H₆O₄ component of formula:


2. A colored liquid composition for highlighting, the compositioncomprising water and a coloring element, wherein the water content byweight lies in the range 10% to 30% and wherein the compositioncomprises at least 40% of a liquid component having surface tensiongreater than 40 mN/m, wherein the liquid component having surfacetension greater than 40 mN/m is a C₄H₆O₄component of formula:

and wherein the water content is about 10% and the C₄H₆O₄componentcontent is about 80%.
 3. The composition according to claim 1, whereinthe coloring element is a tracer solvent having a fluorescent appearanceunder basic pH, wherein the pH of the composition lies in the range 8 to9.
 4. The composition according to claim 3, wherein the component havingsurface tension greater than 40 mN/m is triethanolamine, and wherein thecomposition further comprises an acid to neutralize in part thetriethanolamine so as to obtain the basic pH.
 5. The compositionaccording to claim 1, further comprising a primary alcohol at a contentin the range 1% to 20% by weight.
 6. The composition according to claim1, further comprising an acrylic resin in emulsion at a content of 2% to15% by weight.
 7. The composition according to claim 1, wherein thecomponent having surface tension greater than 40 mN/m is selected fromthe group consisting of glycerin, sorbitol, glycols, and ethanolamine.8. The composition according to claim 3, wherein the coloring element ishydroxypyrene-trisulfonic acid.
 9. The composition according to claim 4,wherein the acid used to neutralize in part the triethanolamine ishydrochloric acid.
 10. The composition according to claim 2, wherein thecoloring element is a tracer solvent having a fluorescent appearanceunder basic pH, wherein the pH of the composition lies in the range 8 to9.
 11. The composition according to claim 10, wherein the componenthaving surface tension greater than 40 mN/m is triethanolamine, andwherein the composition further comprises an acid to neutralize in partthe triethanolamine so as to obtain the basic pH.
 12. The compositionaccording to claim 2, further comprising a primary alcohol at a contentin the range 1% to 20% by weight.
 13. The composition according to claim2, further comprising an acrylic resin in emulsion at a content of 2% to15% by weight.
 14. The composition according to claim 2, wherein thecomponent having surface tension greater than 40 mN/m is selected fromthe group consisting of glycerin, sorbitol, glycols, and ethanolamine.15. The composition according to claim 10, wherein the coloring elementis hydroxypyrene-trisulfonic acid.
 16. The composition according toclaim 11, wherein the acid used to neutralize in part thetriethanolamine is hydrochloric acid.